NOx Emissions Modelling of Turbofan Engines through Chemical Reactor Network
J.S. Huiskes (TU Delft - Aerospace Engineering)
A. Gangoli Rao – Mentor (TU Delft - Aerospace Engineering)
F. Yin – Graduation committee member (TU Delft - Aerospace Engineering)
P.P. Sundaramoorthy – Graduation committee member (TU Delft - Aerospace Engineering)
T. Eker – Graduation committee member (TU Delft - Aerospace Engineering)
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Abstract
This thesis develops a chemical reactor network (CRN) model for an RQL aero-engine combustor and uses it to study water injection and NOx formation across realistic operating conditions. The model includes parallel primary-zone subzones to represent mixture inhomogeneity, detailed gas-phase chemistry and residence-time based zone sizing. It is validated against ICAO LTO emissions for the CF6-80C2B1F and Trent XWB-84 and reproduces the expected NOx and CO trends, including the idle CO peak.
For each operating point, the combustor geometry is kept fixed while the primary-zone equivalence ratios and the mixing parameter are optimised. This same methodology is applied at cruise using cruise-specific inlet conditions. The CRN predicts NOx within the measured in-flight range; BFFM2 also falls within this band, while P3T3 remains close to it. Only the CRN resolves the internal mixture structure and reaction pathways.
Water-to-fuel sweeps show that water injection consistently reduces NOx, with the strongest effect at high thrust where baseline temperatures are highest. CO increases mainly at idle and approach due to lower burnout temperatures. Reaction-pathway analysis confirms that thermal NO remains the dominant mechanism and that water suppresses existing pathways by reducing temperature and radicals.
Overall, the CRN provides an accurate and computationally efficient framework for analysing water injection and predicting emissions at both LTO and cruise, while resolving the internal combustor processes that are inaccessible to simpler correlation-based methods.